array (array::at, [...]): Mark constexpr.

2011-07-20  Benjamin Kosnik  <bkoz@redhat.com>
	    Daniel Krugler  <daniel.kruegler@googlemail.com>

	* include/std/array (array::at, array::operator[]): Mark constexpr.
	* testsuite/23_containers/array/requirements/
	constexpr_element_access.cc: Add.


Co-Authored-By: Daniel Krugler <daniel.kruegler@googlemail.com>

From-SVN: r176550

libstdc++-v3/ChangeLog

 2011-07-20  Benjamin Kosnik  <bkoz@redhat.com>
 	    Daniel Krugler  <daniel.kruegler@googlemail.com>
 
+	* include/std/array (array::at, array::operator[]): Mark constexpr.
+	* testsuite/23_containers/array/requirements/
+	constexpr_element_access.cc: Add.
+
+2011-07-20  Benjamin Kosnik  <bkoz@redhat.com>
+	    Daniel Krugler  <daniel.kruegler@googlemail.com>
+
 	* include/std/chrono: (system_clock::is_steady): Update to N3291
 	from is_monotonic.
-	(time_point): Add constexpr to nonmember arithmetic operators.
+	(time_point): Mark nonmember arithmetic operators constexpr.
 	* src/chrono.cc: Modify for above.
 	* src/compatibility-c++0x.cc: Same.
 	* testsuite/20_util/time_point/nonmember/constexpr.cc: New.

libstdc++-v3/include/std/array

@@ -35,6 +35,7 @@
 # include <bits/c++0x_warning.h>
 #else
 
+#include <stdexcept>
 #include <bits/stl_algobase.h>
 #include <bits/range_access.h>
 
@@ -150,8 +151,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       operator[](size_type __n)
       { return _M_instance[__n]; }
 
-      const_reference
-      operator[](size_type __n) const
+      constexpr const_reference
+      operator[](size_type __n) const noexcept
       { return _M_instance[__n]; }
 
       reference
@@ -162,12 +163,15 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	return _M_instance[__n];
       }
 
-      const_reference
+      constexpr const_reference
       at(size_type __n) const
       {
-	if (__n >= _Nm)
-	  std::__throw_out_of_range(__N("array::at"));
-	return _M_instance[__n];
+	return __n < _Nm ? _M_instance[__n] : 
+#ifdef __EXCEPTIONS
+	                   throw out_of_range(__N("array::at"));
+#else
+	                   _M_instance[0];
+#endif
       }
 
       reference 

libstdc++-v3/testsuite/23_containers/array/requirements/constexpr_element_access.cc

+// { dg-do compile }
+// { dg-options "-std=gnu++0x" }
+
+// Copyright (C) 2011 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+#include <array>
+
+int main()
+{
+  // array
+  typedef std::array<std::size_t, 6> array_type;
+  constexpr array_type a = { 0, 55, 66, 99, 4115, 2 };
+  constexpr auto v1 = a[1];
+  constexpr auto v2 = a.at(2);
+  return 0;
+}